I'm having a similar problem as the OP, I've noticed in heavy downpours that water will occasionally drip into the passenger footwell from the far bottom corner of the door on my 94 NA, I've pulled the carpet up on the passenger side and found the base of the False Floor Plate as well as the bracket...

Hey, i've just purchased my first MX5 a few days ago, its a '94 1.8 and is running on 14 inch alloys which means 3,500rpm in 5th gear at 100km on the highway. Im sure this isnt right, so could someone please tell me what the factory standard wheel size was for a NZ new 1.8 NA? Cheers